It has long been desired to maximize fuel economy, power and driveability in vehicles while enhancing acceleration, reducing emissions, and preventing hesitation. Accordingly, fuel additives have been developed to improve fuel delivery system performance in order to improve engine performance. For example certain additives are used to keep fuel injectors for diesel and spark ignited engines operating under optimal condition by either keeping them clean or cleaning up dirty injectors. Such additives may include additives that are effective to reduce internal deposits in the injectors.
Hydrocarbyl substituted anhydrides such as polyisobutenyl succinic anhydride (PIBSA) and derivatives are known fuel additives detergents for cleaning up deposits on various parts of a fuel delivery systems. However the cleaning performance of such detergents is often found insufficient for use in newer engines and with fuels designed for such newer engines. For example, engines are now being designed to run on alternative renewable fuels. Such renewal fuels may include fatty acid esters and other biofuels which are known to cause deposit formation in the fuel supply systems for the engines. Such deposits may reduce or completely bock fuel flow, leading to undesirable engine performance.
Also, low sulfur fuels and ultra low sulfur fuels are now common in the marketplace for internal combustion engines. A “low sulfur” fuel means a fuel having a sulfur content of 50 ppm by weight or less based on a total weight of the fuel. An “ultra low sulfur” fuel means a fuel having a sulfur content of 15 ppm by weight or less based on a total weight of the fuel. Low sulfur fuels tend to form more deposits in engines than conventional fuels, for example, because of the need for additional friction modifiers and/or corrosion inhibitors in the low sulfur fuels.
Conventional quaternary ammonium compounds have been found effective in cleaning up certain fuels but are not effective in other fuels. In addition, such compounds have non-covalently bound anions that may lead to other problems such as deposit formation in the fuel from the anionic part of the compound.
Certain quaternary ammonium internal salts have been found to be effective where conventional quaternary ammonium salts lack the performance. However quaternary ammonium internal salts may be ineffective in certain petroleum fuels. Accordingly, there is a need for fuel additives, additive concentrates and fuel compositions that provide improved engine performance in a variety of fuels and engines.
In accordance with the disclosure, exemplary embodiments provide a fuel additive concentrate, a method for cleaning fuel injectors, a method for restoring power to a diesel fuel injected engine, a fuel composition, and a method of operating a fuel injected diesel engine. The additive concentrate includes (a) a hydrocarbyl substituted quaternary ammonium internal salt; and (b) a hydrocarbyl substituted dicarboxylic anhydride derivative selected from a diamide, acid/amide, acid/ester, diacid, amide/ester, diester, and imide. The hydrocarbyl substituent of component (b) has a number average molecular weight ranging from about 450 to about 1500. A weight ratio of (a) to (b) in the additive concentrate ranges from about 1:20 to about 2:1. The additive concentrate is devoid of a reaction product of a hydrocarbyl substituted dicarboxylic acid, anhydride or ester and an amine compound of the formula
wherein R2 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R3 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms.
Another embodiment of the disclosure provides a method of improving the injector performance of a fuel injected diesel engine. The method includes operating the engine on a fuel composition that includes a major amount of fuel and from about 5 to about 500 ppm by weight based on a total weight of the fuel of a synergistic fuel additive. The synergistic fuel additive includes (a) a hydrocarbyl substituted quaternary ammonium internal salt; and (b) a hydrocarbyl substituted dicarboxylic anhydride derivative selected from a diamide, acid/amide, acid/ester, diacid, amide/ester, diester, and imide. The hydrocarbyl substituent of component (b) has a number average molecular weight ranging from about 450 to about 1500. A weight ratio of (a) to (b) in the fuel additive ranges from about 1:20 to about 2:1. When the synergistic additive(s) is present in the fuel, at least about 49% of the power lost during a dirty up phase of a CEC F98-08 DW10 test conducted in the absence of the synergistic additive(s) is recovered. In another embodiment, at least 70% of the lost power is recovered. In still another embodiment at least 100% of the lost power is recovered. The additive concentrate is devoid of a reaction product of a hydrocarbyl substituted dicarboxylic acid, anhydride or ester and an amine compound of the formula
wherein R2 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R3 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms.
A further embodiment of the disclosure provides a method of operating a fuel injected engine. The method includes combusting in the engine a fuel composition containing a major amount of fuel and from about 5 to about 500 ppm by weight based on a total weight of the fuel of a synergistic fuel additive. The synergistic fuel additive includes (a) a hydrocarbyl substituted quaternary ammonium internal salt; (b) a reaction product derived from (i) a hydrocarbyl substituted dicarboxylic acid, anhydride, or ester, wherein the hydrocarbyl substituent of component (b) has a number average molecular weight ranging from about 450 to about 1500 and (ii) a polyamine of the formula H2N—((CHR1—(CH2)n—NH)m—H, wherein R1 is hydrogen, n is 1 and m is 4, wherein a molar ratio of (i) reacted with (ii) ranges from about 0.5:1 to about 2:1; and (c) a metal deactivator selected from the group consisting of tolyltriazole and N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine. A weight ratio of (a) to (b) in the fuel additive ranges from about 1:20 to about 2:1 and a weight ratio of (b) to (c) ranges from 0.5:1 to 5:1. The fuel additive is devoid of a reaction product of a hydrocarbyl substituted dicarboxylic acid, anhydride or ester and an amine compound of the formula
wherein R2 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R3 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms.
Another embodiment of the disclosure provides a fuel additive composition that includes a) an oleyl amidopropyl dimethylamino internal salt; (b) a reaction product derived from (i) a hydrocarbyl substituted succinic anhydride, wherein the hydrocarbyl substituent of component (b) has a number average molecular weight of about 950, and (ii) a tetraethylene pentamine, wherein a molar ratio of (i) reacted with (ii) is about 1.6:1; and c) a metal deactivator selected from tolyltriazole and N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine.
It was surprisingly found the hydrocarbyl substituted anhydrides and derivatives in combination with certain hydrocarbyl quaternary ammonium internal salts may be synergistically more effective for improving injector performance and power recovery (power restoration) than each of the components (a) and (b) alone in the fuel. Hydrocarbyl substituted anhydride derivatives may include among others diacid, mono acid/ester, mono acid/amide, amide, ester, imide, and mixtures.
An advantage of the fuel additive described herein is that the additive may not only reduce the amount of deposits forming on fuel injectors, but the additive may also be effective to clean up dirty fuel injectors sufficient to provide improved power recovery to the engine. The combination of components (a) and (b) may also be effective for improving the fuel delivery system including, but not limited to, reducing fuel filter blockage.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.